Conventionally used methods for detecting the presence and extent of microbial contamination of a liquid, particularly biological fluids such as urine, consist of immersing a dipslide which carries a solid microbial culture medium on one or both sides, into a sample of the liquid, removing the slide and inserting the same into a transport container, and incubating the slide for the microbial growth. The solid culture medium is carried on a plastic paddle, usually on both sides, and the paddle is attached to a screw-cap and inserted into a usually transparent plastic container. One major drawback of this method is that individual colonies can only be obtained within a very narrow range of contamination. Another drawback of this method is that for small volume of tested sample, an effective dipping of the dipslide is hard to achieve. Furthermore, the cap has to be unscrewed and screwed on. In addition, the presence of antibiotics in the sample, for example in urine samples from patients already under antibiotic treatment, interferes with the test, since the whole culture medium is dipped into the sample and it is well known that antibiotics interfere with the growth of micro-organisms colonies.
Another device, such as described in U.S. Pat. No. 4,801,547, is for transferring a portion of the liquid sample to a culture medium by means of a transfer member adapted between two panels carrying culture media on one or both faces. One end of the transfer member is first dipped into the sample and by pulling its other end the sample is smeared onto the culture media at the inside face of the folded panels. The volume of the applied sample is gradually reduced along the support member including the panels. The major drawback of this method is that it is hard to detect low contaminations. In this device, the micro-organisms colonies face towards the inside, which makes them hard to inspect and count. Furthermore, this device is only suitable for sampling, not for dipping, and requires use of both hands of the laboratory technician. The support member needs to be relatively long, in order to achieve the desired reduction in the volume of the applied sample.
It would therefore be desirable to provide an easy to use device, for example operable with a single hand, for detecting the presence of micro-organisms in liquid sample or on a solid surface.
It would also be desirable to provide a microbial contamination detecting device that can be used in multiple modes, for example as a conventional dipslide or for transferring of a sample, or a combination of both.
Furthermore, it is of importance to provide a device that would enable detecting wider ranges of microbial contamination.
In addition, it is desirable to enable isolation of individual micro-organism colonies, especially when the sample contains antibiotics or is highly contaminated, and to combine the quantitative accuracy of the dipping method with the qualitative advantages of isolation of individual colonies in a single device.
Another important feature is the ability to test small volume samples.
It is further important to provide a device which would reduce storage and handling space whether in shipment or during sterilization and incubation.
The present invention is directed to microbial contamination detection devices which overcome the above mentioned drawbacks and attain the desired goals.